Many coating and adhesive materials are most conveniently applied by spraying. For small volume applications, it is often convenient to apply a coating or adhesive material using an aerosol container equipped with a fan spray head producing an elongated spray pattern. "Fan spray", as used herein, will refer to spray patterns which have a major diameter and a minor diameter, with the major diameter being at least twice as long as the minor diameter, as measured at a distance of about 150 to 200 mm from the spray head orifice. Fan spray patterns are therefore different from conventional, "circular" patterns, which, as used herein, will refer to patterns in which the major diameter is less than or equal to twice the minor diameter at a distance of about 150 to 200 mm from the spray head orifice. Various fan spray heads for aerosol containers are or have been commercially available, e.g., models 181, 196, and 197 series fan spray heads from Newman-Green Inc., Model RAR-53 fan spray heads from Aerosol Research Co., model "Danvern Fanspray" heads from Sprayon Products division of Sherman-Williams Co., and the Model 21-468004 Fan Spray Head from Precision Valve Corp.
Some dispersions of elastomers (e.g., cross-linked nitrile rubbers, crosslinked butyl rubbers, and neoprene graft copolymers) have been sold in aerosol containers equipped with fan spray heads of the type described above. In contrast to dispersions of elastomers, solutions of elastomers are very difficult to spray from an aerosol container, either in a fan spray or conventional pattern, particularly when the polymer structure of the elastomer has extensive chain entanglement or high solution viscosity. In general, if a polymer has a number average molecular weight above about 10,000 and generates a solution having non-Newtonian viscoelastic properties, it will be difficult to spray from an aerosol container. Such difficult to spray polymers (which hereafter will be referred to generally as "cohesive polymer solutions") have not been made commercially available in aerosol containers, because it has not been possible to obtain acceptable spray patterns from aerosol containers containing such cohesive polymer solutions at levels greater than a few percent aerosol solids in solution. For example, when a polychloroprene contact adhesive based on "Neoprene AC" (which is commercially available from E. I. duPont de Nemours Co.) is dissolved in a solvent such as methylene chloride and loaded in an aerosol spray container pressurized with a propellant such as dimethyl ether to a standard pressure of 0.17 megapascals, and equipped with a Newman-Green Inc. Model R-10-123 can valve and a Model 197-27-12 fan spray head, an approximately 50 millimeter wide fan spray is obtained at aerosol solids levels below about 4.4 weight percent, and a "squirt" or "firehose" type discharge is obtained at higher aerosol solids levels. A 4.4 weight percent aerosol solids solution of "Neoprene AC"-based polychloroprene contact adhesive packaged in a standard 475 cm.sup.3 aerosol can would provide only about 22.0 grams of solid adhesive product, an amount sufficient to cover two surfaces of an area of only about 3.7 m.sup.2. Such a small amount of product would be commercially unacceptable, as a consumer would primarily be paying for the container and would quickly exhaust the container contents. For these reasons, cohesive polymer solutions have never been successfully marketed in aerosol containers. Instead, where possible, they are crosslinked and sold as aerosol dispersions. Otherwise, the polymer generally is sold in containers such as cans, tubes, and bottles, and is not applied using the convenience of aerosol spray.
Sprayed materials are often applied using aerosol or airless spray heads. Many varieties of aerosol spray head configurations have been used to provide fan spray or conventional spray patterns. These aerosol spray heads have typically operated under a driving force of between about 0.14 and 0.83 megapascals, as measured at 25.degree. C. Many spray head configurations have been used for airless spray applications, under operating pressures which are generally between about 0.1 and 31 megapascals, depending upon the material to be sprayed. For example, adhesives are generally sprayed at greater than about 6.9 megapascals when using airless spray equipment. Among the spray heads used for airless spray applications are spray heads having an elongated orifice recessed in an elongate groove or channel, such as those described in U.S. Pat. Nos. 2,621,078, 2,683,627, 3,647,147, 4,097,000, and Des. 198,356. Such airless spray heads have been used to spray materials such as insecticides, paints, adhesives, and the like. However, orifices of the type disclosed in these patents have not been previously reported for use on aerosol containers, and the teachings of these patents do not indicate that the orifice configuration of the spray heads described therein might have utility for use in spray heads for aerosol containers filled with cohesive polymer solutions.